The present invention relates to a method of making an exhaust-noise attenuation muffler, and to an exhaust-noise attenuation muffler.
Mufflers are used to attenuate the transmission of sound waves in exhaust systems of internal combustion engines. U.S. Pat. No. 2,835,336 describes a silencer or a muffler which includes a shell formed with double walls. The outer wall is formed with spaced grooves to provide a plurality of spaced ridges, thereby maintaining the inner and outer walls at a distance and providing obstructions to interrupt sound waves. The inner and outer walls are made of metal sheets which are joined by an overlapping interlocking seam. Common to conventional mufflers is their substantial weight which is determined by the thickness of the used metal sheets. Typically, the thickness ranges from 0.7 mm to 1.2 mm. This substantial weight of conventional mufflers adversely affects fuel consumption. Also, there are limitations to the design options, as a consequence of the manufacturing process.
It would therefore be desirable and advantageous to provide an improved method of making an exhaust-noise attenuation muffler and to provide an improved an exhaust-noise attenuation muffler to obviate prior art shortcomings.